


Formed in Crest, Bound in Feeling

by Willowlark



Series: Golden Dear [6]
Category: Fire Emblem Series, Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Angst, Combat, F/M, Post-Golden Deer Route (Fire Emblem: Three Houses), Sisters, Spoilers
Language: English
Status: Completed
Published: 2019-10-05
Updated: 2019-10-05
Packaged: 2020-11-24 09:54:30
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,339
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20905724
Author URL: https://archiveofourown.org/users/Willowlark/pseuds/Willowlark
Summary: Post Golden Deer Ending: Claude and Lysithea receive a messenger from Byleth; Catherine has gone missing in the ruins of Fort Mercus on a mission to eliminate crest beasts left behind by Edelgard. They fly out immediately to help, Lysithea deathly worried about the woman she calls her sister...





	Formed in Crest, Bound in Feeling

Claude banks his wyvern low, flying under what was a bridge between towers of Fort Mercus. Lysithea grabs onto his waist behind him at the sharp banking maneuver. Her eyes don’t look towards their flight path, they instead scan the ruins of the fort intently. As they approach the center of the fort Claude brings the wyvern up, flapping heavily for a landing. Lysithea jumps off first, too preoccupied with her objective to cater to Claude’s love of helping her off Robin. He says nothing about it as he brings the wyvern down.

“It’s… likely 1pm now” Claude says, hopping down. He pulls Failnaught from the saddle and straps the Sword of Begalta to his hip. “The messenger said that Teach would make it down here around sundown. We can’t expect Leonie and her troop before tomorrow. If we can find a way under the fort before Teach gets here, we can all go down together and clear a path to Catherine.” Lysithea only nods, her expression twisted with worry.

A messenger had arrived this morning, from the Knights of Seiros. Catherine had gone to investigate reports of crest beasts left over from Edelgard’s machinations a few days prior, only for a single soldier to return late last night. His report, before he collapsed from numerous injuries, told of a secret catacombs under Fort Mercus that contained dozens of beasts Edelgard was experimenting with. The beasts were in such numbers they were able to drive the unit deep into the catacombs and get them lost. He was split from the group and found a way up, so he returned to report and get support for his unit and Catherine. 

Byleth sent a runner to Claude with the same information as the church mobilized, knowing Claude would be able to deploy just a bit sooner. Not to mention that Lysithea and Catherine are close, having Lysithea on the battlefield was an absolute need. 

“We’ll find her, don’t you worry. Being lost is more of a danger to her than any crest beast” Claude says easily, hoping to relief some the fears flashing through his wife’s eyes. She returns a half hearted smile and he knows he wasn’t very successful. 

“Worst case I can warp her out if she’s injured…” Lysithea says, her eyes still scanning the ruins for a clue as she runs through scenarios in her head. Claude frowns before taking a heaving breath to steel himself.

“Lyssi.” He says, and she turns at her name. “I know you don’t want to hear this, but you don’t have your crests anymore,” Claude watches her expression turn fiery, he speeds up so to get his point across before she starts throwing spells. “And your magical aptitude went down after we removed your crests. I know you’re still well above the average mage but please, please remember you aren’t as powerful as you were during the war.”

“And so I should let Catherine die?” Lysithea growls. She knows what he wants to say, but her concern for Catherine clouds her judgement. 

“No no, I didn’t…” Claude grimaces. He places his hands on her shoulders and looks right into her eyes. “Lysithea, I couldn’t bear to lose you. If that means I have to be the one who points out the strength you’ve lost, and you’ll hate me for it, so be it. You’re as intelligent as I am my love, together we’ll find a way to Catherine. I simply fear you relying on power you don’t have anymore spelling your death.” Claude says. He watches her eyes slowly lose their edge. It’s familiar expression, one he’s worn as many times as she. The two of them have strong wills and a lot of pride, and they’ve long mastered the art of communicating around that pride.

“… I’ll be careful Claude. Come, we’re wasting time.” Lysithea says, giving her husband a quick kiss and turning towards the ruins. Claude smiles, a pavlovian response to her lips, and remounts his wyvern.

“You’ll do a perimeter sweep first?” Lysithea calls up to Claude. 

“Aye, did you have a theory for the interior search?” He calls back.

“Mm.” She nods. “I want to check where the towers used to stand. That’s the mostly likely access point for a catacomb, based on castle designs I’ve seen.” Claude nods at her, and flies off for the perimeter of the fort.

“Being one of the largest forts in Fodlan… Fort Mercus had at least 6 towers though…” Lysithea mutters, before making her way to the north tower.

* * *

The north and north west towers were absolute busts. Lysithea wasn’t able to to find a single trace of the missing knights or her ‘big sister’ Catherine. Lysithea looks idly at the crest of charon scar on the back of her hand, remembering an encounter not long after the Professor and Claude performed the latter’s miracle cure.

_Catherine had stormed into the Monastery infirmary, much to Manuela’s annoyance. Catherine was pissed, the lines on her face made it oh so clear. She marched up to Lysithea’s bedside._

_ “Why didn’t you tell me your crest was killing you.” She growled out._

_ “… I didn’t tell anyone really. Not until the war, where I told Claude and the Professor so they’d be prepared fighting those who sliver in the dark.” Lysithea replied. _

_ “So you let me prattle on about how we’re sisters because of the crest of charon while that same crest was going to kill you.”_

_ “I…” Lysithea swallowed. “That was one of the good things about my crests. They were net negatives, but… that was one light in the dark.” Catherine was quiet for a few moments. She stared as Lysithea, as the younger woman fidgeted, wondering what she needed to say to reassure the knight that everything was better now, and they didn’t have to be crest of Charon sisters anymore… _

_ Lysithea heard the bed creak at that moment, as Catherine sat down next to her and wrapped her arms around the mage. _

_ “I’d have hated for our bond to have been formed on such a terrible thing for you. I’m glad it was a sweet thing, rather than bitter.” Catherine said. “Crest or not Lysithea, you’ll always be a little sister to me.” Lysithea sniffled for only a moment before she began to cry, returning Catherine’s hug. _

The memory makes Lysithea smile for a moment, before frowning. She needed to find a clue soon, before it got dark. She could see the western tower a few hundred yards before her and she picked up the pace towards it. Overhead she can hear Claude flying nearby, and the crack of rubble beneath her…

Lysithea looks down to the rubble she’s standing on shifting wildly. It drops down, apparently stacked in a hole that leads underground, and begins to cave into the underground section with the addition of her weight on the pile. She flails as Claude looks on from above, sliding underneath the surface with a scream. The rubble follows behind her, resealing the way she entered the passageway she finds herself in.

Lysithea groans, picking herself up from the floor and rubbing where she bashed her shoulder against the hard stone. There’s a loud thump above her and she can hear Claude yelling.

“Lyssi!” He bellows at the top of his lungs. 

“I can hear you, and I’m fine Claude” she yells back. 

“What the hell happened?” 

“I think… I found the catacombs” Lysithea says, looking down the passage she’s in. She unsheathes her Levin Sword, letting the crackling electricity along the blade serve as her light source.

“Wonderful. There’s no way I can get through this entrance without help, there’s too much blocking the way.” Claude calls.

“At least we found an entrance” Lysithea.

“Look at you, ever the optimist” Claude jokes. Lysithea smiles lightly. He’s not as worried as he was when she fell. 

“Maybe I’d have more luck finding a way up, rather than finding a way down” Lysithea calls after a moment.

“Or you’ll find Edelgard’s pet projects in a dark catacomb without backup” Claude says dryly. 

“I’m already in a dark catacomb without backup, and her I’m pinned in a dead end” she quips back. Claude doesn’t immediately respond. She presses her advantage. “I might find Catherine as well, which gives me backup. The benefits of heading in outweigh that of sitting here.”

“It’s risky” is all Claude replies. Lysithea frowns. 

“I know. We’re armed for war Claude, we knew there’d be risks in coming here. The war may be long over but I don’t think either of us slacked in our training.”

“… I just expected to be by your side if there was to be a fight” Claude says, barely audible through the rubble. 

“With you by my side, we could fight Nemesis twice over my love” She says, meaning every word. “That said, as Nemesis is in a different castle, I think it’ll be fine”

“…” Claude says nothing for a moment. Just as Lysithea starts to question if he’s still there, she hears his reply.

“I trust you Lysithea. Always have. If you can find a way up, shoot a spell off into the air so I can join you, and I’ll direct the knights that way. Otherwise I’ll put them to work clearing this entrance.”

“Sounds like a plan. The man with the plan as always my love.” She replies. 

“Your man with the plan, as you may recall.”

“And don’t you forget it” She teases, and the two laugh. There’s a pregnant pause.

“Good luck Lysithea” Claude says.

“I love you too Claude” Lysithea replies, and she heads further into the tunnels.

* * *

It took about a half hour of wandering before Lysithea ran into a crest beast. She turns the corner and jolts back as soon as she sees the massive black creature, stomping up and down the hall. She takes a deep breath and readies Seraphim in her mind, letting the faith spell fill her thoughts. She turns the corner just as it turns around, it’s solid mask face expressionless as it roars. Lysithea looses the spell, the feathered ball piercing right into the monster’s face. It stumbles and falls as it roars again, this time in pain, though Lysithea thinks they always sound like they’re in pain. The barrier on the monster broke due to the magic’s anti-monster properties, so Lysithea lifts her Levin sword, the electricity unleashed down the blade from the hilt, the bolt slamming into the beast. It screeches in pain and dissipates into nothing, leaving behind only the shattered pieces of the fake crest stone that made it.

Lysithea sighs. It wasn’t a powerful beast to be sure, but she still felt good about being able to eliminate it so quickly. As if attracted to her relief, two more masks pop appear at an intersection ahead of her, one from the left and right. The beasts roar and rip around the corner, barely managing to not trip over each other. Lysithea quickly raises her hand to unleash Seraphim, the spell blasting into one of the beasts. It’s barrier make up seems different then the one prior and it continues forward despite the chunk of flesh blown off by the holy magic. Lysithea launches a third Seraphim at the other, which thankfully isn’t as resilient. It trips and falls much like the first one to appear, and in doing so it trips the resistant one. 

Lysithea switches gears, letting the familiar feeling of Reason flow through her as she casts Luna Λ on the one that resisted Seraphim. The image of a moon appears before the creature just as the spell crashes into it, the resistance piercing magic destroying it without difficulty. The remaining beast charges through the mist of it’s comrade, forcing Lysithea to duck a claw swipe. She rolls forward, her Levin sword cutting through the monsters gut as she does. It roars, always in pain, trying to spin in the tight hallway. As soon as it’s masked head gets turned around it is met with a bolt of electricity from Lysithea’s sword, which eliminates the beast. Lysithea holds for a moment, sword thrusted forward, the point not three feet from where it’s face once was. She holds her breath, waiting for another crest beast to roar it’s way into the hallway.

Moments pass and nothing happens, giving Lysithea the chance to untense her body. She leans against the wall, catching her breath. Bless Catherine for teaching her so much sword play. The knight of Seiros took a personal interest in her training after they had bonded over the crest of Charon, and that personal interest involved forcing Lysithea into some martial combat training. Back then Lysithea had been staunchly against it, knowing her body could start to fail her at anytime and not wanting all the training put to waste by that. Magic was safer, and made use of her crests to set her abilities well beyond the rest. 

Catherine ignored every single one of those arguments and distracted her from studying until she agreed to practice with Catherine every week. It turned out to be a great decision, as Lysithea discovered swordplay was surprisingly enjoyable. The art of reading an opponent, figuring out their next move and responding accordingly suited her (something she later learned she had in common with Claude) and Catherine trained her on how to get her body to move in accordance to her observations. After a couple months Lysithea found herself enjoying the training, so much so she kept up with it even after the Academy was torn apart by Edelgard’s machinations. By the time the war started, she got a hold of a Levin sword, which compensated for her weak muscles with magic and gave her the ability to protect herself at close range. It saved her ass a few times in the war itself. 

Certainly has saved her since Claude cured her of her crests as well. She can no longer use Thyrsus, her primary weapon in the war, due to her lack of a Gloucester crest. Lorenz says he’ll take good care of it but… Lysithea sighs. She’s let her thoughts run enough, and she’s long caught her breath. She makes for deeper into the catacombs, hoping to find anything other than more crest beasts.

* * *

“How many of these things did Edelgard fit down here?” Lysithea groans, frustrated. She’s lost count of how many crest beasts she’s fought now, wandering through the catacombs. She’s long exhausted her ability to cast Seraphim, and many of her higher tier dark magic spells. She’s been trying not to think too hard about that, but it’s starting to become an issue. She didn’t have much talent for keeping time underground, so she had no idea if the Knights had arrived to help Claude get down here… or if Claude and the Knights would be able to find her this far in.

She sighs and turns the next corner, only to fall backwards as a blade thrusts into where her head was. She scrambles backwards, her Levin sword coming to the ready, waiting for the beast to turn around the corner and… Her mind catches up with her through the adrenaline and she realizes crest beasts can’t use blades. 

“Catherine!” Lysithea whips around the corner with a shout. The shout disarmed the senior knight, whose eyes are wide at the sight of her crest sister coming around the corner. Catherine is battered, her outfit torn in a variety of places and deep claw gashes visible in the holes, her chest plate dented heavily, and her face and hair are utterly matted with dust, grime and blood. She’s leaning against the catacomb wall when Lysithea sees her, and she slumps down to the floor almost immediately.

“By Seiros, Lysithea I could have killed you” Catherine croaks. Lysithea crouches down in front of Catherine.

“I had you right where I wanted you” Lysithea quips and Catherine smirks.

“Claude is rubbing off on you, you used to be such a serious girl” 

“It’s… hard not to pick up some of his habits” Lysithea says with a sheepish smile. “Forget about me, are you alright? Where’s the rest of…” Lysithea trails off seeing the shadow fall over Catherine’s face.

“I’m… not great. There’s a fruit cocktail of poisons in my system that even my crest is having trouble keeping at bay, and I ran out of Vulnerary… yesterday? It feels long enough to have been a full day. I’ve lost track of time, to be frank.” 

“I can heal the physical wounds, at the very least…” Lysithea says as her one healing magic flows to her hands. It take most of her castings for the day simple to close up all the gashes. “You’re lucky you didn’t get further infections, that Vulnerary probably saved your limbs.” Lysithea says.

“It also saved my life, if I hadn’t been able to swing Thunderbrand I’d be lunch meat by now” Catherine adds dryly. 

“Touche” Lysithea says, closing the last of Catherine’s wounds. She frowns. “I… can’t do much for the poisons. Marianne is the healer, my focus was always…”

“Combat, just like your big sister. Oorah” Catherine says, making a light punching motion with her cheer. Lysithea can see how tense Catherine’s muscles are in the movement. 

“Yes, though it certainly seems like you aren’t up to any of that” Lysithea says, leaning back.

“Well, too much of a good thing is bad for you right?” Catherine laughs, though her eyes confirm Lysithea’s statement.

“Let’s get you to an out of the way corner, and when Claude and the Knights get into the catacombs they’ll be able to handle the rest” Lysithea says. She stands up, brushing dust and bone of her dress before extending a hand to Catherine. The knight takes it, pulling herself up slowly. 

“Sounds like a plan” Catherine says and the two women head off back the way Lysithea came from. Lysithea lends Catherine a shoulder and it doesn’t take them too long to find a long corridor that leads to a dead end. Lysithea sets Catherine down against the end of the hall, hoping that any beast that comes by the corridor entrance won’t be able to spot them this far down. It’s quiet for a few moments, Lysithea settling into watching while Catherine shifts uncomfortably. Eventually, the silence is cut.

“So are you still afraid of ghosts or…?” Catherine asks. Lysithea nearly drops her sword as she groans. 

“Is now really the best time for such a question?” Lysithea drawls over her shoulder.

“Well. We are in a catacomb. Makes some sense to me.”

“If I was still scared of ghosts, like I was when I was a little girl, telling me about them would having me running away terrified. I am your only hope of not being eaten alive by monsters. Did that really not process for you?” Lysithea scolds. She doesn’t make eye contact, instead continuing to keep watch.

“Not really.” Catherine says with a small shrug. Lysithea only replies with a sigh. It’s quiet again, at least until Lysithea does reply. 

“Besides. I can kill a ghost with magic. It’ll be fine” she almost mumbles. Catherine can barely hear it but it causes her to laugh wildly, at least until the stitch in her side has her wincing in pain.

“Ahahaha, you still are, aren’t you? You’ve slain resurrected saints and demonic beasts at that! You think a ghost will stop you?”

“I can’t know magic will affect a ghost until I see one!” Lysithea shouts back. “Give me a break, we all have our weak points!”

“Name even one weakness of mine as mundane as a fear of ghosts!” Catherine laughs back.

“I do recall one time you had to wear a dress and…” Lysithea starts, smirking and glancing side eye at Catherine as the older woman’s color leaves her face

“Alright alright, fine. Maybe it’s not the best time to bring it up” Catherine grumbles. Lysithea gets her chance to laugh. She takes one last look at the long corridor and turns, coming to sit next to Catherine.

“It’s been a long time since we had a chance to joke like this.”

“That Professor of yours is a real slave driver after all” Catherine laughs. “Don’t get me wrong, I enjoy all the work. It keeps me from missing Lady Rhea.”

“Does the Professor’s vision of the church not measure up to Lady Rhea’s?” Lysithea asks.

“It’s not that. I just… miss Rhea. She gave my life purpose when I had pretty much nothing. I’ll always be thankful for that.” Catherine says. Lysithea only hums in response. She didn’t have the heart to tell Catherine, much like Claude, she had her suspicions of Lady Rhea long before everything did come to light. 

“You keep busy too, don’t you? You’re a married woman after all!” Catherine says with a small jab of an elbow. Lysithea chuckles lightly.

“Yes, we have a designated quota of 4 arguments a day and have to find the time to make up each one before bed. It’s quite the life” Lysithea says with a smile on her face.

“Better than you were right after the war” Catherine says, and Lysithea turns to face her once crest sister, a little surprised. “You were so… listless after Nemesis was defeated. I realize now you must have been waiting to die.” Lysithea winces at Catherine’s words. “Then Claude disappeared and I didn’t know how much longer I’d have you. Right after losing Lady Rhea… My answer was to avoid you, distance myself so that when you did go… it wouldn’t hurt so much.” Catherine says wistfully. Lysithea’s mouth is wide and her lip trembles, before she wraps her arm around the older knight.

“I…” Lysithea starts before a finger comes to her lips.

“It’s okay Lyssi. We all had baggage after the war. We needed space and time, to find ourselves again. I always, always knew you’d be like a sister to me to my dying breath.” Catherine says. Lysithea gaps for a moment.

“… It’s not fair for you to be the wise one” Lysithea says with a mock pout. 

“I get a few moments to show off all the experience I’ve garnered” Catherine says with a mock flex. 

“That’s more like the lunkhead sister I know” Lysithea says, unable to keep a giggle from her lips to deliver the line as sarcastically as she wanted to. 

“Just because I can’t chase you down now doesn’t mean I won’t pull that hair of yours-“ Catherine jokes, cut off by Lysithea jumping up and launching a Miasma spell down the corridor. A beast shakes off the attack, prompting a second Miasma from Lysithea with another step forward. The second spell breaks it’s barrier and Lysithea points her Levin sword at the hole, unleashing lightning into the beast. It trips and falls not 10 feet from Lysithea. Before it can get it’s footing, Lysithea steps up and slams the sword through the beast’s Mask, letting the Levin sword electrocute the monster from the inside out. 

“… Maybe I won’t mess with you anymore” Catherine quips as the beast dissolves. 

“Claude learned that lesson in school, how could it have possibly taken this long for you?” Lysithea says. She giggles lightly as Catherine laughs, and Lysithea takes up watch once again.

* * *

“You need to leave, Lysithea” Catherine says, her voice raised and dripping with annoyance. Lysithea doesn’t reply immediately, heaving as she catches her breath, surrounded by the dust of another crest beast that came down the corridor.

“I… told you… I wasn’t going to leave” Lysithea says through her breaths.

“That was the last of your magic reserves wasn’t it? I’ve noticed you counting” Catherine says.

“… I don’t need magic for this” Lysithea says, though her heart isn’t in the rebuttal. Things were about to get very difficult, unless she’d already killed everything down here. Her hopes weren’t high for that though. 

“Damnit Lysithea, you can still get out of here with the Levin sword and bring help! It’s not going to do Claude or Byleth any good to find us both dead down here!” Catherine says. She’s desperate and it’s making her angry. Her eyes are wide and her voice has an edge to that’s a mix of fear and rage. Lysithea hold up a hand behind her. A few moments of silence gives both women the chance to hear footsteps coming towards them. 

“Ly-“ Catherine calls out before a crest beast barrels down the hallway. Lysithea takes up a combat stance, loosing lighting from the Levin sword. The shot arcs, hitting the beast in the side. While it roars in pain, it’s charge doesn’t stop and Lysithea leaps to the side to avoid the pouncing claws of the beast. She slashes the claws in the front of her once, then ducks as they swipe towards her. She thrusts upward from her crouch, letting the Levin sword pump electricity into the claw. Before the beast’s barrier can break the sword locks up, unable to channel any more magical power. Lysithea’s eyes go wide and she tries to pull the blade from it’s claw, only to have the crest beast whip the claw to the other side of the hall, dragging Lysithea along with it. She screams as she slams into the opposite wall and she loses her hold on the sword. Lysithea is slow to stand, using the wall as a support to get to her feet and move back towards Catherine. The beast is distracted by trying to shake her sword out of it’s claw, which gives Lysithea the momentary reprieve. It doesn’t last and it slams it’s claw to the ground, snapping the Levin sword.

“Lysithea please. Don’t die here for nothing” Catherine pleads behind the mage. “I’m ready for this, I have been for a long time, it’s knight’s duty!” She tries to stand, her body refusing to move correctly. “Lysithea!” Catherine nearly cries as the beast stomps down the hall. 

Lysithea turns behind her and closes the distance to Catherine. Her eyes are fiery and her face is set in a scowl. “I’m not a child anymore Catherine” She says quietly as she picks up Thunderbrand. Catherine’s eyes go wide and she attempts to reach for Lysithea, flashes of Miklan Gautier’s transformation going through her head. 

* * *

Lysithea swings Thunderbrand around between her and the beast and… the beast is gone. So is Catherine, and the corridor. She finds herself in a dark void, only the gold steel… or rather bone of Thunderbrand contrasting the dark.

“Your blood… is familiar…” a soothing voice echoes. It doesn’t appear to come from anywhere. The way it lingers in her mind, floating through her thoughts… It’s almost as if she said it herself. “But it is changed. No longer my own, or of my brothers…” Brothers? Lysithea can’t think through the voice. The echoes of the voice fade as it says nothing and her thoughts begin to race. Thunderbrand is… the heart and bones of a child of the goddess. This just might be…

“You no longer bear my blood, yet to hold my bones and heart in your hands.” The voice somehow booms while still being comforting and soft. “You lack protection, I could easily overwhelm your body in retribution for the sins against me and my kin… Yet. You are familiar. You once bore my blood, I remember it. My bearer let you use this blade a few times, years ago” Lysithea finds herself nodding in response, as if she had no choice but to answer. “Yes… and you were a careful wielder. Respectful. And guided Mother on her quest against the heathen… You shall have my blessing. For your past virtues outweigh the sins of your ancestry.” 

* * *

Thunderbrand explodes with light, the heart lighting up and the golden blade shining like a beacon in the dark. Lysithea shouts a feral cry, swinging the blade upwards with two hands. She cuts deep into the beast’s mask and it scrambles backwards. She shouts again as she sweeps low, cutting the claws off the monster. It stumbles on the nubs it has for feet, and Lysithea brings Thunderbrand down on it’s head when it does. The beast dissolves into the dust, and Lysithea pants and heaves, not daring to drop the heavy blade. It’s moments before she’s caught her breath, and even more before either her or Catherine could find the resolve to speak.

“Ly…sithea?” Catherine asks hesitantly. 

“I suppose…” Lysithea says as the light from Thunderbrand fades. “We’re still crest sisters, somehow.” Catherine sighs in relief, hearing Lysithea’s voice and not that of a monster as Lysithea turns to her. “Though I think I’ll leave Thunderbrand to you, that was…” Lysithea trails off. There’s a strange hole in her memory, like something happened when she took up the sword, yet she can’t place what happened at all. Still… she counts her blessings they both survived the encounter. 

“Damn straight you will!” Catherine outright yells. “I’m not in the business of loaning it out, especially to people without crests! You could have died!”

“I told you Catherine…” Lysithea says quietly. “I’m not a child anymore.”

“You are my goddess damned sister! I don’t care if your skin is wrinkled and your bones ache, you’re always going to be a child to me!” Catherine growls. Lysithea pauses for a moment… finally realizing why Catherine is so insistent. It’s not that she doesn’t think Lysithea can do it… 

“I’m sorry to have worried you” Lysithea says. Catherine looks at her for a moment longer before the rage melts off her face and leaves only a tired smirk.

“You better be” Catherine says simply. The two lock up as they hear footsteps again. They quickly realize it’s not the loud pounding of a beast but the patter of multiple people, and around the corner come Byleth and Claude. The tension in their shoulders fades, smiles coming to their faces.

* * *

The Knights had built a temporary camp by the time Lysithea and Catherine were lead out of the catacombs. Seteth and Flayn took to healing the toxins in Catherine’s system while Marianne tended to Lysithea’s wounds. When they finished they left the two above ground, joining Claude and Byleth underground to deal with the crest beasts still remaining. Between Leonie’s mercenary troupe, the reassembled Golden Deer House, and the Knights of Seiros, anything left down their didn’t stand a chance.

“I suppose we’re out of the action then” Catherine sighs next to Lysithea.

“Yes… Though we had a lot of action as it was. Hannerman is going to want to run tests I’m sure, I haven’t expended this much magic since we removed my crests.” Lysithea rubs her temple. Hannerman means well but he’s always been a tad… tactless. 

“Consider it your punishment for overtaxing yourself on my account” Catherine says dryly. Lysithea gives her a side eyed glare and Catherine looks away. “That said… Thank you, Lysithea.”

“Anytime.” Lysithea says, smirking just a little bit at the cowed knight. 

“Don’t get cocky, little sister. I still have a powerful weapon over you.”

“Oh? What could that be?” Lysithea folds her arms in challenge.

“I could tell Claude exactly how reckless you were down there.” Catherine smirks and it wipes the smirk right off Lysithea’s face. “Oh, I can just imagine how henpecked you’ll be for the next few months as he worries endlessly about-“

“Alright, alright, fine. It’s a draw” Lysithea groans. Catherine laughs. 

“As long as you don’t make any more attempts at taking the name Thunder Lysithea, it’s a deal.” Catherine says, throwing an arm around the smaller woman. Catherine jostles them together in a hug which Lysithea, after an exaggerated huff, returns. It was a relief, to both the women, that despite Lysithea losing the crest of Charon… Their bond as sisters was formed in their feelings for one another, rather than the blood they once shared.

**Author's Note:**

> This got long lol
> 
> I first thought Lysithea's support with Catherine would have been about Catherine forcing Lysithea to do some Martial combat training, secretly prepping Lysithea to maybe wield Thunderbrand. Then I did the supports and it was about them being sisters and it was equally as cute~ (The first scenario worked it's way in there though) 
> 
> This may be the first fic in the series that doesn't involve Claude rubbing Lysithea's scars at some point Weird thought
> 
> More Headcanons (This is harder than I thought)
> 
> \- [ ] Marianne and ignatz are so at peace with one another they can go a whole day without a word. For outsiders, it’s quite unnerving
> 
> \- [ ] Multiple women in the alliance army crushed on Raphael during the war. He never noticed. 
> 
> \- [ ] Claude has nightmares about some of the more risky plans he’s executed failing and getting his friends killed. 
> 
> \- [ ] Marianne is the primary physician for everyone in the Deer. Hannerman, as a crest scholar, has consulted heavily on Claude’s cure of Lysithea’s crests and afterwords on the health of her magic circuits. The usually mild mannered Marianne is extremely protective of Lysithea with Hannerman, knowing Hannerman’s inquisitive nature 
> 
> \- [ ] Claude has a habit of overthinking basic tasks, making contingency plans and maximizing efficiency on things like making tea. Lysithea immediately takes over the task when she catches him doing it, because he takes too long


End file.
